Support means and adjusting means for a disc brake



Nov. 12, 1968 HODKINSON ET AL 3,410,372

MEANS AND ADJUSTING MEANS FOR A DISC BRAKE Si JPPORT 3 Sheets-Sheet 1Filed NOV.

NOV. 12, 1968 HODKlNsON ET AL 3,410,372

SUPPORT MEANS AND ADJUSTING MEANS FOR A DISC BRAKE Filed Nov. 10, 1965 5Sheets-Sheet 2 v 0; 2 3 S S m 0 Oh x2. t no Ow 0m Om an r511 N MON E on4 Q Q 3 m Q rn 0v NOV. 12, 1968 H, HODKlNsON ET AL 3,410,372

SUPPORT MEANS AND ADJUSTING MEANS FOR A DISC BRAKE Filed Nov. 10, 1965 5Sheets-Sheet 5 United States Patent 3,410,372 SUPPORT MEANS ANDADJUSTING MEANS FOR A DISC BRAKE Harold Hodkinson, Finham, and AnthonyCoiin Evans, Binley, England, assignors to Duniop Rubber CompanyLimited, London, England, a corporation of Great Britain Continuation ofapplication Ser. No. 516,187, Nov. 10, 1965. This application Jan. 11,1968, Ser. No. 697,240 Claims priority, application Great Britain, Nov.19, 1964, 47,057 64 16 Claims. (Cl. 18873) ABSTRACT OF THE DISCLOSUREThis invention comprises inter alia, a disc brake having a combinationof mechanical and hydraulic brake applying mechanisms which are operableindependently of each other so that the brake can be either mechanicallyor hydraulicially operated. An adjustably elongated member forms part ofthe thrust connection between the friction element and both thehydraulic and mechanical applying mechanisms, to compensate for wear ofthe friction member which occurs during braking.

This invention relates to disc brakes, and this application is acontinuation in whole of application Ser. No. 516,187, filed Nov. 10,1965, now abandoned, for Disc Brakes.

One object of the invention is to provide a disc brake which is operableboth by a hydraulic brake-applying mechanism, and a mechanicalbrake-applying mechanism, and which is therefore suitable for use WhereOperation by a hydraulic foot brake mechanism and also by a mechanicalhand brake mechanism is required.

According to the invention a disc brake comprises a rotatable disc, anonrotatable support, a rigid caliper mounted on the support andrestrained from rotational movement about the axis of the disc andhaving a pair of limbs straddling a periphery of the disc, a pair offriction elements associated one with each limb of the caliper so as tobe engageable with the sides of the disc, and a brake-applying mechanismfor pressing at least one of the friction elements towards the disc, thebrake-applying mechanism comprising a thrust member mounted in theassociated limb of the caliper and guided for axial movement relative tothe caliper to apply a thrust to the associated friction element, athrust device, and a lever mechanism arranged to transmit the thrustfrom the thrust device to the thrust member, the thrust member beingadjustable in length and means associated with the lever mechanism beingprovided to effect automatic adjustment of the length of the thrustmember to take up clearances arising from wear of the friction elements.

According to one aspect of the invention, a hydraulically-operatedthrust device and a mechanically-operated thrust device are provided,and means associated with the lever mechanism is provided for effectingautomatic adjustment of the length of the thrust member to take upclearances arising from wear of the friction elements.

The thrust member may comprise a pair of screwthreadedly engagedportions which are rotatable relative to one another by a ratchet deviceoperable whenever the movement of the lever to apply the brake exceeds apredetermined amount, the arrangement being such that relative rotationof the portions of the thrust member takes place on release of thebrake.

Three embodiments of the invention will now be described, by way ofexample, with reference to the accompanying drawings, in which:

'ice

FIGURE 1 is an axial cross-sectional view of a disc brake;

FIGURE 2 is an end view of the brake shown in FIG- URE 1;

FIGURE 3 is a partly cross-sectional radial view of the brake shown inFIGURES 1 and 2;

FIGURE 4 is a partly cross-sectional radial view of an alternative discbrake according to the invention;

FIGURE 5 is an axial cross-sectional view of the brake shown in FIGURE4;

FIGURE 6 is a partly cross-sectional radial view of a furtheralternative disc brake according to the invention.

A single-sided disc brake 1 (see FIGURES 13) for use on the rear wheelsof a motor vehicle comprises a disc 2 mounted for rotation with a wheel,and a nonrotatable caliper 3 mounted on a nonrotatable anchoring andlocating component 5 at one side of the disc 2 and having a pair oflimbs 6 and 7 straddling the outer periphery of the disc 2. The caliper3 is slidably mounted so as to be movable in the axial direction of thedisc on a pair of pins 8 and 9 as described in the specification of ourco-pending US. patent application No. 506,151, now abandoned.

The limb 6 of the caliper 3 carries a friction element 10 fixed to thelimb, and the other limb 7 carries a friction element 11 which ismovable axially relative to the caliper, the movable friction element 11consisting of a friction pad 12 mounted on a backing plate 13 which isengaged by one end of a thrust member 14 slidably mounted in a bore 15of the caliper.

The thrust member comprises an outer portion 16 in the form of a pistonslidable in the bore 15 and provided with a rubber seal 17 to excludemoisture and dirt from the interior of the bore, and an inner portion 18in the form of a screw engaging a screw-threaded axial bore 19 in thepiston portion 16. The portion 16 is nonrotata-bly secured to the backing plate 13, and a ratchet 20 is formed on the head of the screwed innerportion 18 to enable the portion 18 to be rotated by means to bedescribed, relatively to the portion 16 to adjust the length of thethrust member.

A hydraulic brake operating mechanism 21 consists of a cylinder 22,formed as a blind bore in the caliper, and a piston 23. The piston 23 isformed with a socket 24 into which one end of a push rod 25 is inserted,the push rod 25 being received at its other end in a socket 26 formed inthe inner portion 18 of the trust member to convey the thrust from thehydraulic mechanism 21 to the thrust member.

The push rod 25 is formed with a flange 27 between its ends forengagement by a lever 28 pivotally attached at one end to a pin 29mounted in a block 36 fixed to the caliper. The lever 28 is formed fromtwo side portions 31 and 32 extending one each side of the push rod 25and each engaging the flange 27 thereof. The free end of the lever 28 isprovided with a roller 33 engageable by a cam 34 which is mounted on apin 35 rotatably supported in the caliper and provided with an operatinglever 36 and a cable 37 for connection to a vehicle hand brake operatingmeans.

The brake 1 can be operated by the hand brake operating mechanismindependently of the hydraulic brake operating mechanism 21, the lever28 being rotatable about its pivot pin 29 by the action of the cam 34 topress on the flange 27 of the push rod 25.

Automatic adjustment of the length of the thrust member 14, tocompensate for friction pad wear, is provided by a pawl 38 pivotallymounted on the portion 31 of the lever 28 by means of a pin 39 andengaging the ratchet 20. A pawl spring 40 is secured at one end to thepawl 38 and at the other end to a pin 41 fixed to the lever portion 31,the spring 40 tending to urge the pawl in a counterclockwise directionas seen in FIGURE 1, and thus tending to turn the ratchet in such adirection as to cause the inner portion 18 to be screwed outwardly fromthe outer portion 16 to increase the length of the thrust member.Movement of the pawl in the inoperative state of the brake is preventedby the engagement of a peg 42 (FIG- URE 3), fixed to the pawl, with anabutment 43 fixed to the caliper by a bolt 44.

When the brake is applied, either by the hydraulic mechanism or by themechanical brake-applying mechanism, the lever 28 is tilted towards thedisc about its pivot pin 29. The peg 42 is prevendted by the abutment 43from moving towards the disc and the pawl 38 is thus moved in aclockwise direction about its pivot pin 39 against the opposition of thespring 40. If the brake clearance is such that the movement of the leverrequired to apply the brake exceeds a predetermined value, the pawl willre-position itself behind a fresh tooth on the ratchet and on release ofthe brake will be drawn by back by the spring 40 to rotate the innerportion 18 of the thrust member so as to increase the effective lengthof the thrust member.

FIGURES 4 and 5 show a disc brake which is similar in its generalconstruction to that shown in FIGURES 1-3 but which incorporates analternative brake operating mechanism.

The disc brake 50 comprises a caliper 51 of a similar kind, and axiallyslidably supported, in a similar manner to that shown in FIGURES 13, onpins 52 and 53 attached to a nonrotatable Support and extending axiallyadjacent the outer periphery of a disc 54. One limb 55 of the caliper 51has a friction element 56 fixed thereto, and the other limb 57 has afriction element 58 associated therewith and movable axially towards thedisc. A thrust member 59 is slidably mounted in the limb 57 of thecaliper, and is of a similar kind to that of the brake shown in FIGURESl3, comprising an outer screw-threaded portion 60 and an innerscrew-threaded portion 61. The inner portion 61 has a head 62 formed asa ratchet, as in the embodiment described above. An annular sheet-metalretraction spring 63 is engaged at its inner edge beneath the head 62and is supported at its outer edge in a recess 64 formed in the caliper.

The brake 50 is provided with a hydraulic operating mechanism 65 and amechanical operating mechanism 66 acting at opposite ends of a lever 67which is pivotally supported between its ends on a fulcrum 68 secured tothe caliper. The hydraulic mechanism 65 comprises a guided piston 69slidable in a bore 70 of the caliper, and the mechanical operatingmechanism 66 comprises an operating lever 71 for connection to a handbrake operating mechanism and a cam 72 rotatable by the lever 71 to movethe lever 67 in the counterclockwise direction as seen in FIGURE 4.counterclockwise movement of the lever 67 can thus be effected by eitherof the mechanisms 65 and 66, and such movement of the lever 67 developsa brake-applying thrust which is conveyed to the thrust member 59 by apush rod 73 received in sockets 74 and 75 formed respectively in thelever 67 and the inner portion 61 of the thrust member 59.

A pawl 76 is pivotally mounted in the caliper about an axis passingthrough the lever fulcrum 68 and is engaged with the ratchet 62. A pawlspring 77 is secured at one end to the pawl 76 and at the other end to apin 78 which is secured to the lever 67 and which forms a pivot for asecond lever 79. One end of the lever 79 engages an abutment 80 on thecaliper and the other end engages a lug 81 formed on the pawl 76.

In operation, counterclockwise movement of the lever 67 presses the pushrod 73, thrust member 59 and friction element 58 towards the disc, thebody of the caliper moving axially under the reaction force set up whenthe friction element 58 contacts the disc to bring the other frictionelement 56 into engagement with the opposite side of the disc. Thesecond lever 79 is rotated, during brake application, in a clockwisedirection as seen in FIGURE 4, causing a corresponding counterclockwisemovement of the pawl 76. It will be noted that the effect of the lever79 is to provide an increased angular movement of the pawl 76 comparedwith that which would be obtained if it were rotated by engagement of afixed abutment on the caliper with the lug 81.

When the movement of the lever 67 to apply the brake exceeds apredetermined amount, the pawl 76 is repositioned behind a fresh toothon the ratchet 62, and on release of the brake is drawn back by thespring 77 to rotate the ratchet so as to increase the effective lengthof the thrust member, as in the embodiment described above. Theretraction spring 63 is deformed resiliently on application of the brakeand draws the thrust member back when the brake is released, thusreturning the lever 67 to its original position. The spring 77 alsotends to return the lever 67 to its initial position, the tension of thespring tending to rotate the pawl 76 and thus the second lever 79 in adirection to urge the lever 76 in a clockwise direction as seen inFIGURE 4.

FIGURE 6 shows a disc brake of similar general construction to thebrakes described above but incorporating a further alternative operatingmechanism. The brake 90 comprises a caliper 91, disc 92, and frictionelements 93 and 94, the caliper 91 being axially slidably supported onpins 95 and 96 secured to a nonrotatable support 97. A thrust member 98is axially slidably supported in the caliper and comprises inner andouter screwthreadedly engaging portions 99 and 100 respectively. Anannular retraction spring 101 is provided as in the embodiment shown inFIGURES 4 and 5.

The brake 90 is provided with a hydraulic operating mechanism 102 and amechanical operating mechanism 103 which, as in the previously describedembodiment, act at opposite ends of a lever 104. The lever 104, is,however, not pivotally supported on a fulcrum attached to the caliper:the mechanism 103 provides a fulcrum for the lever when the brake isoperated by the mechanism 102 and the mechanism 102 provides the fulcrumwhen the mechanism 103 is operated. The lever 104 engages the thrustmember 98 at a point between its ends to transmit the brake operatingthrust to the thrust member.

An automatic adjustment mechanism constructed similarly to that shown inFIGURES 4 and 5 is provided to compensate for friction pad wear. Theadjustment mechanism comprises a pawl 105, a ratchet 106, a pawl spring107, and a second lever 108 arranged tooperate in a similar manner tothe adjustment mechanism of the brake shown in FIGURES 4 and 5.

What is claimed is:

1. In a disc brake having a rotatable disc, the structure comprising anonrotatable support, a rigid caliper mounted on said support andrestrained from rotational movement about the axis of the disc andhaving a pair of limbs straddling the periphery of said disc, a pair offriction element associated one with each limb of the caliper so as tobe engageable with the sides of the disc, and a brake-applying mechanismfor directly pressing at least one of the friction elements towards thedisc, said brakeapplying mechanism being mounted on the caliper andcomprising a thrust-member mounted in the associated limb of the caliperto apply a thrust to the associated friction element, a fluid pressureoperated thrust device aligned with the thrust member and actinngthrough said thrust member to apply the associated friction element, alever pivotally attached at one end to said caliper and also attached tosaid thrust member to be movable by said fluid pressure operated thrustdevice, a mechanical brake operating mechanism associated with the otherend of the lever, said lever having a force transmitting connection withsaid thrust member to transmit the thrust from the mechanical brakeoperating mechanism to the thrust member independently of said fluidpressure operated thrust device, the thrust member being adjustable inlength and comprising an outer cylindrical member nonrotatably securedto the associated friction element and slidably engaging the walls of anaxially formed bore in said caliper, the outer cylindrical member beingheld by the bore against transverse movement relative to the axis of thedisc, and an inner rotatable member in screw-threaded engagement withthe outer member, and adjustment means associated with the lever toeffect automatic adjustment of the length of the thrust member byrotation of the inner member thereof.

2. A disc brake structure in accordance with claim 1 wherein said thrustmember includes an abutment connection with said operating lever whichis bifurcated to impart a balanced thrust force thereon, said thrustmember including a flanged push rod providing an articulated connectionbetween said thrust member and said fluid pressure operated thrustdevice.

3. The disc brake structure in accordance with claim 2 including a pawloperatively carried by said lever and engageable with a coacting portionof said rotatable member to effect rotation of said inner member wherebysaid adjustment means is eifective to control of the length of saidthrust member.

4. The disc brake structure in accordance with claim 1 wherein saidouter cylindrical member is in direct thrust engagement with one of saidfriction elements and is responsive to both said mechanical and saidhydraulic operating mechanisms.

5. In a disc brake including a rotatable disc, the structure comprisinga nonrotatable supporting frame work comprising a substantially flatsupport member having two radially extending outwardly projecting limbsforming a notch therebetween disposed alongside said brake disc adjacentone of the radially extending side faces thereof, a pair of axiallyfixed anchoring-and-locating members one on each of said limbs which areangularly spaced apart and extending axially to provide torquetakingsurfaces located along one side only of said disc and disposed closelyadjacent thereto, a pair of friction elements having means providingslidable support relatively to said anchoring-and-locating members anddisposed one on each side of said disc to be engageable with oppositebraking surfaces of said disc, one of said friction elements consistingof an elongated friction liner and backing having slidable torque-takingremote ends adapted to operatively transmit anchoring thrust to saidsupport member through angularly spaced complementary locations disposedclosely adjacent said disc and located adjacent said pair of combinationanchoring-and-locating members, a rigid caliper carried by saidanchoring-andlocating members and proportioned to be positioned betweenthe said anchoring-and-locating members and having surfaces adapted tobe complementary with said torque-taking surfaces and slidably supportedthereon at one side of said rotatable disc, said caliper having a pairof limbs straddling the said periphery of the disc, a brake applyingmechanism supported by one limb of said caliper and arranged to beoperated to press the friction element associated therewith toward thedisc and the other limb disposed in operative engagement with the otherfriction element to move it toward the disc under the reaction set up onthe caliper by said brake applying mechanism as said other limb is drawntoward said anchoring-and-locating members, and other friction elementbeing disposed between said other limb and the assoicated side of saiddisc, said caliper being freely movable in an axial direction relativeto said anchoring-and-locating members and positively located withrespect to the radial and circumferential directions with respect tosaid friction elements,

means associated with said lever to eflfect operation of said secondbrake applying mechanism.

6. The brake structure in accordance with claim 5 including meansassociated with said lever mechanism for effecting automatic adjustmentof the length of the thrust member to take up clearances arising fromwear of the riction elements.

7. A disc brake according to claim 6 wherein the thrust member comprisesa pair of parts in screw-threaded engagement with one another androtatable relatively to one another to adjust the axial length of thethrust member.

8. A disc brake according to claim 7 wherein one of the screw-threadedparts is prevented from rotating and the other part is rotatable and isengageable by the means associated with the lever mechanism to effectautomatic adjustment of the length of the thrust member.

9. A disc brake according to claim 8 wherein the thrust member comprisesan outer cylindrical part axially slidable 1n a bore of the caliper andnon-rotatably secured to the associated friction element, and an innerpart in screwthreaded engagement with the outer part.

10. A disc brake according to claim 8 wherein the rotatable partcomprises a ratchet, and a pawl is provided to engage the ratchet toeffect said automatic adjustment, the pawl being associated with thelever mechanism.

11. A disc brake according to claim 10 wherein a pawl sprlng is providedto urge the pawl in a direction which would tend to rotate the ratchetand the rotatable part to increase the length of the thrust member,abutment means being provided to urge the pawl against the spring onapplication of the brake, the arrangement. being such that movement ofthe lever mechanism beyond a predetermlned amount in applying the brakeas a result of excessive clearance arising from Wear of the frictionelements will cause the pawl to engage a fresh tooth on the ratchet andon release of the brake the pawl will be urged by its spring to rotatethe ratchet to effect automatic adjustment of the length of the thrustmember to take up the clearance.

12. A disc brake according to claim 11 wherein the pawl is pivotallymounted on the lever mechanism so as to be movable in a plane parallelto the plane of the movement of the lever mechanism.

13. A disc brake according to claim 12 wherein the lever mechanismcomprises a lever pivotally attached at one end to the caliper andassociated with the thrust member at a position between its ends, thepawl being pivotally mounted on the lever and being engageable by anabutment on the caliper, to effect the said automatic adjustment of thelength of the thrust member.

14. A disc brake according to claim. 13 wherein the pawl spring issecured at one end to the pawl and at the other end to the lever.

15. A disc brake according to claim 13 wherein a mechanical brakeoperating mechanism is provided at the end of the lever remote from itspivot.

16. A disc brake according to claim 15 wherein the mechanical brakeoperating mechanism comprises a cam mechanism.

References Cited UNITED STATES PATENTS 2,940,554 6/ 1960 Cameron 188-96X 2,966,964 1/1961 Brueder 188-73 3,059,731 10/1962 Gancel et a1. 188-733,169,608 2/1965 Press et al 188-72 3,211,263 10/1965 Harrison 188-72 X3,236,336 2/1966 Harrison 188-73 3,269,490 8/1966 Swift 188-72 MILTONBUCHLER, Primary Examiner.

G. E. A. HALVOSA, Assistant Examiner.

